one of scotland yard's top officers resigned. two years ago john yates ruled there was no re-open the investigation, and it was that botched decision that cost the job of britain's top cop. the head of the scotland yard stepped down amid public outrage yesterday. >> as commissioner i carry ultimate responsibility for the position we find ourselves in. with hindsight i wish we had judged some matters involved in this affair differently. i didn't, and that's that. >> cnn's dan rivers is in london where all eyes turn to tomorrow's testimony before lawmakers. tell us why. >> reporter: well, they want to know how far up the chain this went, this whole phone hacking scandal. who knew what in the murdoch empire? that's what they hope to get to the bottom of tomorrow. rupert and james murdoch themselves will be appearing before politicians here for a grilling as well as those two -- their former executive rebecca brooks will appear separately because she was arrested late last night and detained and questioned for some 12 hours. she's ou